-LRB- CNN -RRB- -- An internationally renowned paleontologist will plead guilty to stealing dinosaur bones from federal land , his attorneys said in a court filing .

Paleontologist Nate Murphy is expected to plead guilty to stealing fossils from federal land .

Nate Murphy , whose famous finds include Leonardo , one of the best-preserved dinosaurs in the world , will make that plea in federal court in Billings , Montana .

Earlier this month , Murphy pleaded guilty to state charges of stealing a fossil from private land in order to sell it . An expert cited in that case said Murphy 's find was worth between $ 150,000 and $ 400,000 .

The self-taught dinosaur expert , who is director of vertebrate paleontology at the Judith River Dinosaur Institute , could face jail time .

Murphy and his attorney did not immediately respond to phone messages Friday from CNN .

Jessica Fehr , lead prosecutor in the case , said the U.S. Attorney 's Office would not comment until after the plea is entered .

In court papers , federal prosecutors say Murphy knowingly took fossils from federal property between about August 2006 and August 2007 . The `` paleontological resources '' were said to be worth at least $ 1,000 .

In the state case , Murphy pleaded guilty to a felony charge of theft . As part of the plea , the state recommended Murphy 's sentence be deferred for five years .

Douglas Erwin , president of The Paleontological Society and curator of the Smithsonian 's National Museum of Natural History , said `` theft of fossils from pubic lands has long been a problem . ''

In a written statement sent to CNN on Friday , he said such thefts `` can often result in the loss of important scientific information and the disappearance of specimens that belong to the public .

`` At the same time , however , fossil collecting , particularly of common invertebrate fossils , has been a pastime enjoyed by many for decades , and is an important way of connecting people with their natural heritage . ''

An omnibus public lands bill , which the U.S. Senate passed Thursday , includes penalties for fossil theft from public land .

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Attorney says well-known paleontologist will plead guilty to stealing dinosaur bones

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Nate Murphy , of the Judith River Dinosaur Institute , has made major fossil finds

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Murphy is accused of taking fossils from federal lands in Montana

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Smithsonian : `` Theft of fossils from pubic lands has long been a problem ''